Plasma display panel comprising a first external electrode for each digit and a second external electrode for each segment

ABSTRACT

In an external electrode plasma display panel for a plurality of digits, transparent first electrodes are placed in front of the segment-shaped voids of the respective digits formed in a central plate and second electrodes are placed at the back of the respective voids of the digits. The second electrodes for the corresponding voids of the digits are connected in series, with lead wires extending to the edge of the panel from the second electrodes for the respective voids of the digit placed at least at one of both ends of the digits.

United States Patent 1191' Miyazaki Nov. 19, 1974 PLASMA DISPLAY PANEL COMPRISING A FIRST EXTERNAL ELECTRODE FOR EACH DlGIT AND A SECOND EXTERNAL ELECTRODE FOR EACH SEGMENT [75] inventor:

[73] Assignee: Nippon Electric Company, Limited,

Tokyo, Japan 22 Filed: May 17, 1973 21 App]. No.: 361,327

Togo Miyazaki, Tokyo, Japan [30] Foreign Application Priority Data May 23, 1972 Japan... 47-60166 May 23, 1972 Japan.... May 23, 1972 Japan 47-60168 [52] 11.8. C1 313/484, 315/169 TV [51] Int. Cl. H0lj 7/42 [58] Field of Search 313/109.5, 220, 210; 315/169 TV, 169 R [56] References Cited UNITED STATES PATENTS 3,435,270 3/1969 VOd1Cka 3113/1095 3,652,891 3/1972 Janning 313/220 3,694,693 9/1972 Holz 313/169 TV 3,711,733 1/1973 Skutt 313/169 TV 3,720,452 3/1973 Kupsky 313/109.s 3,742,279 6/1973 Kupsky 313/169 R 3,764,429 10/1973 Janning 313/109.5

Primary ExaminerJames W. Lawrence Assistant Exdminer-D. C. Nelms Attorney, Agent, or Firm-John M. Calimafde 5 7] ABSTRACT In an external electrode plasma display panel for a plurality of digits, transparent first electrodes are placed in front of the segment-shaped voids of the respective digits formed in a central plate and second electrodes are placed at the back of the respective voids of the digits. The second electrodes for the corresponding voids of the digits are connected in series, with lead wires extending to the edge of the panel from the second electrodes for the respective voids of the digit placed at least at one of both ends of the digits.

2 Claims, 3 Drawing Figures PAIENImuv 1 91914 'FIG.2

PLASMA DISPLAY PANEL COMPRISING A FIRST EXTERNAL ELECTRODE FOR EACH DIGIT AND A SECOND EXTERNAL ELECTRODE FOR EACH SEGMENT BACKGROUND OF THE INVENTION This invention relates generally to displays and more particularly to an external electrode plasma display panel for a plurality of digits or letters.

A plasma display panel generally includes a central plate having a plurality of through hole sets, a front plate, and a rear plate. The three plates are typically made of glass and are substantially identical in shape. These plates are stacked and sealed together around their peripheries. Each of the through hole sets consists of a predetermined number of segment-shaped voids arranged in a predetermined configuration, such as a figure of eight. The voids are filled with an ionizable gas, which is commonly neon or a mixture of neon and argon. The pressure of the ionizable gas in the voids may be several hundred Torr. The front and the rear hole sets, a front plate, and a rear plate which are stacked and sealed together around their peripheries. Each of the through hole sets consists of a predetermined number of segment-shaped voids arranged in a predetennined configuration and filled with an ionizable gas. A plurality of substantially transparent first electrodes are placed on the surface of the front plate facing the central plate and a plurality of second electrodes are placed on the surface of the rear plate facing the central plate. The first electrodes are placed at least at those portions of the front plate surface which confront the respective ones of the through hole sets. The

first electrodes are covered with a substantially transplates are provided with first and second electrodes, re-

spectively, placed on their surfaces facing the central plate at the positions of the respective voids. The first electrodes should be substantially transparent. The first and the second electrodes are covered with first and second insulating layer means, respectively. The first insulating layer means should be substantially transparent, and the second insulating layer means should preferably be colored black. The electrodes having the voids therebetween in which gas discharge is caused to occur are supplied with pulses of a high repetition frequency. Access to the electrodes for application therebetween of the pulses is provided by lead wires connected thereto through the through holes formed through the front and the rear plates on which the electrodes having the respective lead wires are placed. This construction is objectionable from the viewpoint of manufacture. Alternatively, the corresponding electrodes for the respective digits are connected in parallel by means of electroconductive connections formed on the front and the rear plates on which the parallel connected electrodes are placed. This results in an increase in the electrostatic capacity of the plasma display panel and a resulting increase in the power consumption of the pulses. With either of these means for providing access to the electrodes, it is necessary to initially test the plasma display panel to determine if the connection of te lead wires or the electroconductive connections to the electrodes is defective.

SUMMARY OF THE INVENTION:

It is therefore an object of the present invention to provide an electrode plasma display panel for a plurality of digits or letters, which can be easily manufactured.

It is another object of this invention to provide a plasma display panel of the type described, which has a reduced electrostatic capacity and which accordingly requires less electric power for providing the display.

It is still another object of this invention to provide a plasma display panel of the type described, which can be easily tested to determine if access to the electrodes from outside the panel is perfect.

According to this invention, a plasma display panel includes a central plate having a plurality of through parent first insulating layer at least at those portions of the first electrodes which confront the respective voids of through hole sets. The second electrodes are placed at those portions of the rear plate surface which are in registry with the respective ones of the voids of the through hole sets. The corresponding ones of the second electrodes are connected in series along the rear plate surface by means of electroconductive connections. A plurality of lead wires extend from the respective second electrodes placed in registry with the respective voids of a predetermined at least one of the through hole sets towards the periphery along the rear plate surface. The second electrodes for the through hole sets are covered with a second insulating layer at least at those portions of the second electrodes which are in registry with the voids of the through hole sets.

To the accomplishment of the above and to such further objects as may hereinafter appear, the present invention relates to a plasma display panel, substantially as defined in the appended claims and as described in the following specification taken together with the accompanying drawing in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view on one embodiment of the present invention with the thicknesses of the elements of the embodiment shown exaggerated;

FIG. 2 is a plan view of a rear plate for use in the embodiment depicted in FIG. 1, together with the second electrodes, electroconductive connections, and lead wires formed on one surface of the rear plate; and

FIG. 3 is a perspective view of an exhaust pipe for use in manufacturing a plasma display panel.

DESCRIPTION OF THE PREFERRED EMBODIMENT:

Referring to FIG. 1, an external electrode plasma display panel for a plurality of digits comprises a central plate 11, a front plate 12, and a rear plate 13. The central plate 11 is a rectangular soda glass sheet and is about 15-200 microns thick. The central plate 11 is provided with a row of through hole sets 111, 112, and lln. Each of the through hole sets consists of a predetermined number of segment-shaped voids arranged in a predetennined configuration, such as, as

shown in the embodiment of FIG. 1, a figure of eight.

first electrodes 121, 122, and l2n on one of its surfaces to cover, when superposed on the central plate 11 with the front plate surface having the first electrodes 121, 122, and l2n directed toward the central plate 11, at least those portions of the front plate surface which are in registry with the through hole sets 111, 112, and 11n. To form the first electrodes 121, 122, and l2n, a substantially transparent electroconductive film, such as a film of stannic oxide, is placed on the front plate surface and is subsequently divided into separate electrodes 121, 122, and l2n by etching, by electrolysis, or mechanically.

Referring to FIGS. 1 and 2, the rear plate 13 is a glass sheet having substantially the same outline as the central plate 11 and is about 3 mm thick. The rear plate 13 is preferably longer than the central plate 11 in the direction of the row of the through hole sets 111, 112, and lln. The rear plate 13 is provided with a plurality of second electrode sets 131, 132, and 13n on one of its surfaces. Each of the second electrode sets 131, 132, and 13n consists of a plurality of separate second electrodes A, B, C, D, E, F, AND G. The number of the separate second electrodes is equal to the number of segment-shaped voids of each of the through hole sets 111, 112, and 11n. The second electrodes A through G should bein substantial registry with the segment-shaped voids of the through hole sets 111, 112, lln when the rear plate 13 is superposed on the central plate 11 with the rear plate surface having the second electrodes A through G directed toward the central plate 11. The corresponding second electrodes, such as the second electrodes A, of the second electrode sets 131, 132, and 13n are connected in series by electroconductive connections 14 formed on the rear plate surface. A plurality of lead wires 15, the number of which is equal to the number of second electrodes A through G of each of the second electrode sets 131, 132, and 13n, extend from the respective second electrodes A through G of each of the second electrode sets 13] and 13n placed on both ends of the row of the second electrode sets 131, 132, and Br: to the adjacent edge of the rear plate 13. The corresponding lead wires 15 on both ends of the second electrode row are thus electrically connected through the second electrodes A through G and the electroconductive connections 14. Preferably, the connection between each pair of the corresponding lead wires 15 should be as short as possible. The second electrodes A through G, the electroconductive connections 14, and the lead wires 15 may be formed at the same time by screen printing. More particularly, commercially available silver paste may be applied to the rear plate surface through a pattern for printing these elements and then baked in an electric furnace at a temperature between 500C and 600C. In a manner known in the art, an exhaust hole 16 is formed, as by ultrasonic machining or drilling, through the rear plate 13 at a position offset from the second electrodes A through G, the electroconductive connections 14, and the lead wires 15, before forming the latter elements on the rear plate surface. The exhaust hole 16 is for subsequent attachment to an exhaust pipe 17 (FIG. 3).

Referring again to FIG. 1, the first electrodes 12], 122, and l2n are provided with terminals 181, 182, and 18n, respectively, as shown. Terminals 181, 182, and l8n are preferably silver layers applied to the respective first electrodes 121, 122,

and l2n by screen printing, by a brush, or otherwise. The first electrodes 121, 122, and l2n are covered with a first insulating layer 21 at least at their portions confronting, when the front plate 12 is superposed on the central plate 11 in the manner mentioned above, the through hole sets 111, 112, and lln, except at their portions on which the terminals 181, 182, and 18n are formed. To form the first insulating layer 21, powder glass may be spread over the exposed surfaces of the first electrodes 121, 122, and l2n by screen printing, sedimentation, electrodeposition, spraying, or other technique and then fired into a unifonn glass layer in an electric furnace at a temperature between 500C and 600C. The thickness of the first layer 21 may be between 10 microns to 30 microns. The first layer 21 should preferably be transparent to provide a clear display. Similarly, the second electrodes A through G are covered with a second insulating layer 22 of a like thickness. The second insulating layer 22 may also cover the electroconductive connections 14 and is preferably colored black in order to provide a clear display.

With the front plate assembly and the rear plate assembly placed on both sides of the central plate 11, and with the exhaust pipe 17 brought into registry with the exhaust hole 16, glass fn't is applied to the periphery of the plate stack and the abutting end of the exhaust pipe 17 and is subsequently glazed at a temperature between 400C and 450C. The voids within the plate stack are evacuated in a known manner and then filled with an ionizable gas, such as neon or a mixture of neon and argon, at a pressure of several hundred Torr. The exhaust pipe 17 is eventually sealed with glass frit to complete the external electrode plasma display panel. The plasma display panel is operable by applying pulse voltages to the front plate terminals 181, 182, and 18n and to the rear plate lead wires 15 selectively in the manner known in the art as dynamic driving.

An important feature of the external electrode plasma display panel according to the present invention resides in the structure of the second electrodes A through G, the electroconductive connections 14, and the lead wires 15. The integral construction of these elements remarkably facilitates the manufacture of the plasma display panel. The shortest possible connections of these elements reduce the conductive elements which do not contribute to the display, and also reduce the electrostatic capacity between the first and second electrodes. The latter fact reduces the electric power of the voltage pulses that is consumed by the panel without contributing to the display. In addition, it is possible with the lead wires 15 extended to the opposing edges of the rear plate 13 to quantitatively test if there are any defects, such as a short, breakdown of the connection, or anomaly in the resistance in the second electrodes A through G, the electroconductive connections 14, or the lead wires 15.

While the present invention has thus far been described in conjunction with a preferred embodiment, it will readily be possible for those skilled in the art to modify the embodiment in various manners. For example, the first electrodes 121, 122, and l2n may be made of titanic oxide or indium sesquioxide. They may be formed of an opaque material into a mesh structure. It should therefore be understood that the expression substantially transparent used in this specification and the appended claims does not refer to the optical nature of the material of the first electrodes 12], 122, and 1211 but to the first electrodes per se. The second electrodes A through G may be made of gold, platinum, an alloy of molybdenum and manganese, or any other conductive material. The central plate 11 may be a mica sheet or a metal sheet having an insulating coating. The rear plate 13 may be a ceramic plate. The insulating layers 21 and 22 may cover only the surface portions of the first electrodes 121, 122, and 1211 and the second electrodes A through G that confront the segment-shaped voids 111, 112, and lln.

What is claimed is:

1. In a plasma display panel for a plurality of identical characters including:

first and second supporting members,

a plurality of identical sets of character-forming electrodes on said second supporting member, a common electrode for each set on said first supporting member, and means associated with the common electrode to enable a first electric potential to be applied thereto,

the improvement which comprises: electroconductive means on said second supporting member in coplanar relation to said characterforming electrodes for connecting corresponding electrodes in each set in series so that corresponding electrodes in each set and the connecting electroconductive means therebetween form a continuous line segment free of branches, and

plural lead wires extending from first ends of each of the serially connected character-forming electrodes disposed at one end of said continuous line segment for applying a second electric potential to the corresponding electrodes connected to said each character-forming electrode coincident with said first potential, whereby a potential difference of predetermined magnitude may be produced between the energized corresponding electrodes and a common electrode for a selected set.

2. The plasma display panel of claim 1, further comprising second lead wires extending from the second ends of each of the serially connected characterforming electrodes disposed at the other ends of said continuous line segments, said second electric potential being also applied to said second lead wire. 

1. In a plasma display panel for a plurality of identical characters including: first and second supporting members, a plurality of identical sets of character-forming electrodes on said second supporting member, a common electrode for each set on said first supporting member, and means associated with the common electrode to enable a first electric potential to be applied thereto, the improvement which comprises: electroconductive means on said second supporting member in coplanar relation to said character-forming electrodes for connecting corresponding electrodes in each set in series so that corresponding electrodes in each set and the connecting electroconductive means therebetween form a continuous line segment free of branches, and plural lead wires extending from first ends of each of the serially connected character-forming electrodes disposed at one end of said continuous line segment for applying a second electric potential to the corresponding electrodes connected to said each character-forming electrode coincident with said first potential, whereby a potential difference of predetermined magnitude may be produced between the energized corresponding electrodes and a common electrode for a selected set.
 2. The plasma display panel of claim 1, further comprising second lead wires extending from the second ends of each of the serially connected character-forming electrodes disposed at the other ends of said continuous line segments, said second electric potential being also applied to said second lead wire. 